1  /* Increase the size of a dynamic array in preparation of an emplace operation.
       2     Copyright (C) 2017-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <dynarray.h>
      20  #include <errno.h>
      21  #include <intprops.h>
      22  #include <stdlib.h>
      23  #include <string.h>
      24  
      25  bool
      26  __libc_dynarray_emplace_enlarge (struct dynarray_header *list,
      27                                   void *scratch, size_t element_size)
      28  {
      29    size_t new_allocated;
      30    if (list->allocated == 0)
      31      {
      32        /* No scratch buffer provided.  Choose a reasonable default
      33           size.  */
      34        if (element_size < 4)
      35          new_allocated = 16;
      36        else if (element_size < 8)
      37          new_allocated = 8;
      38        else
      39          new_allocated = 4;
      40      }
      41    else
      42      /* Increase the allocated size, using an exponential growth
      43         policy.  */
      44      {
      45        new_allocated = list->allocated + list->allocated / 2 + 1;
      46        if (new_allocated <= list->allocated)
      47          {
      48            /* Overflow.  */
      49            __set_errno (ENOMEM);
      50            return false;
      51          }
      52      }
      53  
      54    size_t new_size;
      55    if (INT_MULTIPLY_WRAPV (new_allocated, element_size, &new_size))
      56      return false;
      57    void *new_array;
      58    if (list->array == scratch)
      59      {
      60        /* The previous array was not heap-allocated.  */
      61        new_array = malloc (new_size);
      62        if (new_array != NULL && list->array != NULL)
      63          memcpy (new_array, list->array, list->used * element_size);
      64      }
      65    else
      66      new_array = realloc (list->array, new_size);
      67    if (new_array == NULL)
      68      return false;
      69    list->array = new_array;
      70    list->allocated = new_allocated;
      71    return true;
      72  }
      73  libc_hidden_def (__libc_dynarray_emplace_enlarge)